Start practicing giving and keeping your word-everywhere.
If you say the job will be complete by the 15th, have it completed by the 15th. If you can’t have it complete by the 15th, say that, and make a new agreement. If you say you’ll be there by 3pm, be there by 3 pm. If you’re running late, call and say that before the fact. Think your customers will appreciate working with you if you do this? You bet they will.
And while you’re at it, don’t make promises that are really safe, that you know you can easily do. If you’re making one, make it big enough to be worth everyone’s time who is listening. It takes courage to stand out like that, but that’s what it takes to get the important work done, whether it’s a co-worker or a customer.
Be bold and use your speaking to take a stand for something courageous, something that’s really wanted and needed. Make a commitment, then go for it.